Force fields and vibrational spectra of M2O and MOH (M = Li,Na) molecules according to data from nonempirical MO-LCAO-SCF calculations

The geometric structure, force fields, and vibrational spectra of M₂O and MOH (M=Li, Na) molecules have been investigated. The size of the d basis on the oxygen atom has a significant influence only on the frequency of the deformation vibration ₃. Experimentally unknown constants of the molecules considered have been evaluated.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 724–728, November–December, 1986.     

Structure and thermodynamics of hydrocarbon liquids: Computer simulation based on rism theory

A system of Ornstein-Zernike integral equations is solved numerically to determine the heats of vaporization ΔH_V of liquid ethane, propane, and n-butane. It is shown that the calculations (the deformations of valence bonds and bond angles in the liquid-phase molecules are ignored) give rather accurate values of ΔH_V, which are in agreement with the corresponding experimental data. On the other hand, it is established that if there are intramolecular rotational degrees of freedom, ΔH_V depends on the angle of internal rotation ϕ. The function ΔH_V(ϕ) is minimum for trans-conformations (ϕ=0) and maximum for cis-conformations (ϕ=180°). Hence, intermolecular interactions stabilize compact (convolute) conformations. The energy of this effect is of the order of 1 kJ/mole. Tver State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 5, pp. 808–813, September–October, 1995. Translated by I. Izvekova     

Influence of the crystallinity of pentasil-type zeolites on their acidity

The acid properties of intermediate products in crystallization of pentasil-type zeolites have been investigated using programmed thermal desorption of ammonia and adsorption of pyridine. It was found that acidity increases with increasing crystallinity due to proton-donor centers. A correlation was established between this change in acidity and methanol TPSR data.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 31, No. 1, pp. 48–51, January–February, 1995.     

Short communication

The diffusion of copper, nickel and cobalt in silicon single crystals during irradiation with MeV protons, was studied under various experimental conditions. Under the irradiation normally used for charged-particle activation radiation enhanced diffusion negligible. The diffusion of radioisotopes caused by thermal effects however, lead to important errors. It is important to control the temperature of the irradiated samples.     

Stereochemistry of 2-substituted 5,6-benzo-1,3,2-dioxarsepines

Russian Chemical Bulletin -     

Determination of micelle structure and charge by neutron small-angle scattering

We present a general method of determining the structure and charge of globular ionic micelles, using neutron small-angle scattering. The micellar solutions may have any concentration within the micellar phase. The method is based in part on an analytic calculation of the interparticle correlations between monodisperse spherical micelles, and we discuss the theory in some detail to justify its application to polydisperse globular particles. Experimental results are presented for several cationic and anionic micellar systems.     

Synthesis and characterization of polymerizable bisphthalonitrile monomers

The reactions of 4-aminophthalonitrile (APN) with 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BPTDA), and with 1,2,3,4-benzenetetracarboxylic dianhydride (PMDA) have been studied to optimize the conditions for the synthesis of monomeric thermosetting bisphthalonitrile compound. Suitable procedures for the synthesis of the two monomers are presented. Elemental analyses, IR spectra, dynamic thermogravimetric analyses, differential scanning calorimetry, ¹H-NMR, and mass spectral studies have been used to characterize these compounds. Preliminary observations show that these materials can be polymerized to give high-temperature-resistant materials.